A2 Science In Society 3.3 Teacher Notes
Page 2 ©The Nuffield Foundation, 2009
Copies may be made for UK in schools and colleges
A2 Science In Society 3.3 Teacher Notes
How Science Works
Ae To judge if there has really been a change in the value of a quantity, we need to take account of both the difference in the mean values and the spread of repeat measurements.
Bf Claims about large groups are usually based on measurements on a sample of the population (all the individuals in the group). The sample should be selected randomly, or carefully chosen to represent the population accurately. Failure to do this will introduce bias.
Bg To investigate the hypothesis that a factor increases the probability of an outcome, scientists compare a sample exposed to the factor with a control sample that is not. To judge that a factor does affect the outcome, the difference must be big enough not to be attributable simply to normal variation.
Ch A scientific theory should lead to predictions that are precise and detailed enough for it to be possible that they can be shown to be false (falsification). A theory is ‘non-scientific’ if it does not make any predictions that could possibly be falsified.
Fb The popular media play a part in providing information, setting the agenda and influencing opinion on issues involving science and technology.
Introduction
This activity is designed to help students think about the differences between good science and pseudoscience. They also review some ideas about chance variation and probability. Their interest is gained by asking them to carry out some widely available tests on aspects of their own brain’s characteristics, some in the classroom and some online. They analyse their group’s data and consider the validity of such tests.
Resources
Access to internet
Scissors, paper
The activity
The activity includes tests which might require sensitivity in some classrooms. The possible link between cross-laterality and dyslexia might be an issue. The test for male/female brains could well disturb some students who are rated by these pseudo-science tests as being less than wholly male or female. The whole point of the activity is to get students to consider how flimsy the base for such tests is, but the labels might still stick. Perhaps students should be warned about how meaningless the tests are before they do them if you feel that they might be troubled.
Science explanations
Kb Within the cortex different regions process signals from different parts of the body and process specific types of input. Several brain regions will be actively involved in any thought process
There are three separate sections: practical tests on left right laterality, web-based tests on left-right brain dominance, a web-based test on male /female brains. Each section includes practical or web tests, information and discussion questions. They can be used independently.
Answers
The questions are almost all discussion points so the answers given here are to support discussion and provide background, they are not model answers.
A - Handedness
1b) For students who are already familiar with the chi-squared test this could be used to find the probability values associated with the observed and expected results of the class. This test will not be examined. The main idea is to give students practice at the concept of probability, and to get a feeling for the degree of variation that might be expected by chance. Some teachers may feel that by carrying out a statistical test students will gain more insight into the notion of statistical significance. See note on statistical significance.
2a) Means that dyslexia is more commonly found among cross laterals than would be expected by chance. (Note however that some research has shown that only 50% of children show the same lateral preference for eye, hand and foot.)
b) Neither statement is necessarily true. An association does not indicate cause. However, it is possible that cross laterality is one of several factors in dyslexia. As there is no clear cut-off point in dyslexia, it is difficult to prove or disprove the second statement.
B - ‘Right brained’ and ‘left brained’ people
3 The revolving figure claims to indicate which hemisphere is dominant, but it is more likely to indicate the activity of the visual cortex at the back of the brain. Also, many people find that the figure can reverse direction.
4 It would be surprising if there were a correlation between visual processing of the revolving figure and the personality tests of the questionnaires. Almost all brain functions use both sides of the brain.
5 The questions seek to find whether you like an orderly and structured environment (supposedly left brain) or whether you prefer chaos and imagination (supposedly right brain). Possible questions:
· Have these questions been validated against fMRI scans of brain activity?
· Is there any theoretical basis for the assumptions behind the questions?
· How reliable are they? (do repeat tests give the same results)
6 There are differences between individuals and between the sexes in the use of different brain areas. However, all people use both hemispheres all the time and this dichotomy (left/right brained) is a great oversimplification, with little or no basis in fact. Brain lateralisation is a valid area of research (often using fMRI). However, the right/left brain idea is widely misused for the promotion of various psychological interventions in the guise of science (pseudoscience). It is an easy-to-understand but invalid concept, and it is therefore likely to mislead people.
a) Both use left brain but females also use right brain.
b) This seems to show that the separation of functions between left and right brain is not absolute. The location of language in left brain seems to apply mainly to males. Females seem to use both sides for a language task. It is thought that male brains may be more strongly lateralised than female brains.
C - Male/female brains
7 The male/female brain test uses a BBC website which is entertaining and has further useful links. It would be instructive to discuss the validity of these tests.
Adding up the scores for all six tests to give an overall score of brain type is somewhat bogus, as it implies that everyone’s brain can be placed on a linear scale from extreme male to extreme female. There are not necessarily any real parallels between measures such as relative length of fingers, spatial awareness and facial attractiveness, though links with testosterone are claimed.
By promoting such tests the BBC is trying to get people interested in neuroscience and psychology, which is commendable, but risks oversimplifying. It might also cause people to worry about where they are on the ‘scale’, even leading some to seek pseudoscientific therapies to make up for their perceived deficiencies.
The differences are likely to be very small, see Figure 3.
8 a) Mean very close, female slightly higher than male
Males have wider distribution (greater standard deviation)
b) Each of these statements could be justified as true or false depending on how the data is used. One could look at the top performers, the mean or the overlap in the majority of the population.
9 The sketch should show two curves very similar to those in Figure 3 but with the mean for females slightly lower than that for males.
December 2009
Page 2 ©The Nuffield Foundation, 2009
Copies may be made for UK in schools and colleges
A2 Science In Society 3.3 Student sheets
Introduction
No two brains are the same, and every brain is constantly changing. In this activity you will be invited to carry out some tests on your own brain and to analyse data from the group. You critically evaluate some of the claims made about the roles of the right and left brain and the differences between male and female brains.
A - Left and Right brain - Laterality
Human brains are lateralised. This means that the two halves of the brain (or hemispheres) carry out somewhat different functions. One expression of this is that we tend to prefer using one hand or one eye more than the other.
Handedness
Make a table with four vertical columns. In the first list ten common tasks which use one hand, e.g. writing, brushing your teeth, shaking hands, waving, throwing a ball etc. Head the next two columns ‘right’ and ‘left’, and head the fourth column ‘dominant eye’. Tick each activity to indicate the hand you normally use for the task. Activities for which you use both hands equally should score half each. Count your score out of ten in the column for the right hand to provide a measure of your handedness. Pool the data for your group (at least 10 people) in one table. Score each person as right handed, left handed or ambidextrous (a score of 5).
Dominant eye
Hold your forefinger vertically at arm’s length. With both eyes open, move the finger from side to side until it is lined up with a vertical structure, such as the corner of the room or the side of a window. Keep your focus on the finger while you do this. Now close one eye, keeping your finger still.
· If the finger appears to jump sideways, you have closed your dominant eye. Close the opposite eye and the finger should keep in line - now your dominant eye is open.
· If the finger keeps in line then you have closed your non-dominant eye.
Alternative method: cut a hole in a piece of paper about the size of a 1p coin, or use a hole punched in file paper. With the paper at arm’s length look at a distant object, such as a clock on the wall, through the hole. Bring the paper nearer and nearer to your face while keeping the object in sight. The eye to which you bring the paper is your dominant eye.
Add the information about which eye is dominant to your handedness table. Analyse the class results to show the frequency of the four different combinations of dominant hand and eye. Display in a 2 x 2 matrix.
Right hand / Left handRight eye
Left eye
You could also check whether there are any links with ‘thumbedness’ and hand/eye dominance. Interlock the fingers of your two hands, as you would when resting your hands on your lap. Note whether your right or left thumb is at the top. Does this match your handedness?
Analysis
1a) What were the commonest combinations in your class?
b) Is there a tendency for right handed people to have a dominant right eye and left handed people to have a dominant left eye?
Even if there is a correlation between the dominance of eye and hand in your class it is quite possible that this is a chance occurrence and that a different group of students would produce a different result. Your requirement as an experimenter is to show that any correlation you observed is a real effect that applies to the population of students and not just to this particular sample of students in your class. The hypothesis that the distribution observed is the result of chance is called the null hypothesis. You have to disprove it. To calculate the numbers you would expect to get by chance work as follows:
· Write the row and column totals beside your 2 x 2 matrix of results as in the example in Figure 1 below.
· Write the total sample size in the bottom right hand corner (20 in this example).
· Work out the number expected by chance for each box by multiplying the row total by the column total and dividing by the sample size. E.g. for the RR box you multiply 13 x 15 and divide by 20. This gives a figure of 9.75 which can be rounded up to 10. The expected numbers are given in brackets in the example.
Figure 1 An example of class results for eye/hand dominance
Hand / NR / L
Eye / R / 12 (10) / 1 (3) / 13
L / 3 (5) / 4 (2) / 7
15 / 5 / 20
Note that you are simply multiplying probabilities here, e.g. multiplying the probability of being right eyed with the probability of being right handed. If the numbers expected by chance differ markedly from your observed numbers, then you can reject the null hypothesis. In the example shown, RR and LL occurred more often then expected by chance. [It is possible to work out a probability value, p-value, for the difference between observed and expected results using a simple statistical test, which your teacher may show you. You will not be examined on how to carry out a statistical test].
Cross laterality
This term means that your dominant eye is on the opposite side from your dominant hand (i.e. you are left eyed and right handed or vice versa). Some psychologists are interested in the links between cross laterality and language ability, and with specific learning difficulties such as dyslexia, though these are by no means confirmed.
2 Some scientists have found that: ‘Cross laterality is associated with dyslexia’.
a) Explain what you understand by this finding.
b) Explain whether the finding suggests that
i) cross laterality causes dyslexia